Breast pumps are well known devices for extracting milk from a breast of a user. A breast pump may be used if the baby is not itself able to extract the milk, or if the mother is separated from the baby, for example if away from the baby at work. The use of a breast pump to extract milk may also be used to stimulate lactation in women with a low milk supply.
Conventional breast pumps make use of a vacuum to induce milk extraction from a nursing mother's breast. The pumping action of the device draws the milk from the teat to a collection vessel, and may be adjusted to the preferences of the lactating female.
A conventional breast pump for extracting milk from a user's breast is shown in FIG. 1. Such a conventional breast pump unit 1 comprises a main body 2 and a feeding bottle 3. The feeding bottle 3 is attached to the main body 2 by a screw fitting.
A vacuum pump unit (not shown) is formed in the main body 2 to create a vacuum, as will be described hereinafter and a handle 4 extends from the main body 2. Breast pumps may be manually operated, for example by squeezing the handle or by operation of a foot pedal. Breast pumps may also be electrically driven by a small electric motor.
A breast receiving funnel 5 is fixedly attached to the main body 2 for receiving the breast of a user. The funnel 5 comprises a mouth 6 and a throat 7. The mouth 6 is open at an upper end and an inner surface of the mouth 6 converges from the upper end towards the throat 7 to form a hollow recess. An insert 8 is insertable in the mouth 6 of the funnel 5 in an attempt to improve a user's comfort and aid the expression of milk.
However, a problem with conventional breast pumps is that users are known to suffer from discomfort or difficulty when using such a conventional breast pump. When an infant feeds from its mother's breast, the baby applies two actions to obtain milk, a sucking action and a peristaltic movement created by the action of the infant's tongue on the teat of the mother's breast, the teat comprising a nipple and areola tissue. The sucking action applies a negative pressure to latch onto the breast and induce milk flow. The infant can also perform a peristaltic stripping motion over the areola and nipple to induce milk flow from the breast. In this motion a rhythmic contraction and expansion motion is performed to induce the milk flow.
The peristaltic (tongue) motion stimulates the hormone-production responsible for the ‘let-down’ reflex which allows milk produced in the milk glands to be released into the milk ducts. Conventional breast pumps do not produce this peristaltic motion, and so a high negative pressure is required to obtain a flow of milk to compensate for the lack of peristaltic movement. Furthermore, the absence of such an action means that extracting milk is uncomfortable and inefficient and does not provide a natural action.
Breast pumps with inserts are disclosed in U.S. Pat. No. 4,249,481 which attempt to apply a peristaltic motion to a breast. However, each of the breast pumps with inserts disclosed in this document have a complicated construction, for example necessitating the use of a double wall insert and applying a pressure differential between the walls of the insert. Therefore, the arrangements shown in this document require a complex construction, such as a plurality of pressure ports, and make it difficult to clean the insert and associated breast pump.